It's been a busy few weeks for flagship phones across all platforms - iOS, Android and Windows. Apple announced the iPhone 6S and 6S Plus first, followed closely by Google and the Nexus 5X and 6S devices. Microsoft then completed the flagship platform line-up with the Lumia 950 and 950 XL.

All three platforms offer various features and functions, as do their flagship handsets, but which device is the right one for you? If you haven't already put yourself into a camp, this feature is for you to help you work out what the different devices offer across the different platforms.

We have crunched the numbers and specs of the Apple iPhone 6S, Apple iPhone 6S Plus, Google Nexus 5X, Google Nexus 6P, Microsoft Lumia 950 and the Microsoft Lumia 950 XL to see what the differences are, and what one device offers over the next.

Starting with designs of these six devices, you'll find all metal bodies on the Apple iPhone 6S and iPhone 6S Plus, as well as the Google Nexus 6P. The Google Nexus 5X, Microsoft Lumia 950 and Lumia 950 XL all come with metal frames and polycarbonate rears.

In terms of physical size, the smallest and slimmest is the iPhone 6S at 138.3 x 67.1 x 7.1mm, but it is worth remembering this device also has the smallest display size. The thickest is the Lumia 950 at 8.2mm.

The largest device overall is the Nexus 6P but only by a fraction measuring 159.3 x 77.8 x 7.3mm compared to the iPhone 6S Plus that sits at 158.2 x 77.9 x 7.3mm. The lightest of the bunch is the Nexus 5X at 138g, while the heaviest is the iPhone 6S Plus at 192g.

The iPhones have the broadest colour offerings with four choices available compared to three for the Nexus devices and two for the Lumia.

The Lumia and Nexus handsets all come with USB Type-C for faster charging and data transfer, while the Apple and Nexus devices come with fingerprint sensors making Google the only one to offer both.

As we mentioned, the Apple iPhone 6S has the smallest display of all the devices being compared here with a 4.7-inch screen. The Microsoft Lumia 950 and the Google Nexus 5X both offer 5.2-inch displays, while the Microsoft Lumia 950 XL and the Google Nexus 6P opt for 5.7-inch screens. The Apple iPhone 6S Plus sits in the middle with a 5.5-inch display, despite being one of the largest handsets in terms of footprint.

So which is the best display? Well this depends on what you consider a good display. Both Lumia devices and the Nexus 6P have Quad HD resolutions, while the Nexus 5X and the iPhone 6S Plus have Full HD. The iPhone 6S drops this down further to 1334 x 750 pixels.

All these numbers translate to the Lumia 950 theoretically offering the sharpest display overall with a pixel density of 565ppi, and the iPhone 6S offering the softest with a 326ppi. It is worth mentioning that we didn't have any complaints about the iPhone 6S display when we reviewed it so bear in mind that numbers aren't the only thing that make a display great.

The Lumia and Nexus devices are AMOLED, meaning vibrant colours and inky blacks. The iPhones are LED so you can expect more realistic colours that are perhaps not as punchy.

A couple of other things to mention here is the iPhones both have what Apple calls 3D Touch, a feature that recognises the force of your finger on the screen to deliver varying functions. Microsoft on the other hand has Glance Screen, which allows users to see various bits of information without turning the display on and therefore preserves battery life if you just want to see the time for example.

Smartphone cameras are always a fun section because despite many manufacturers playing the numbers game, it isn't all about the megapixels. Each of these devices has its own features and functions and performance is affected by various factors.

Nevertheless, for comparison purposes, the rear snapper megapixel winner are the Microsoft Lumia devices, with both the 950 and 950 XL sporting a 20-megapixel sensor. The front-facing winner is the Google Nexus 6P that comes with an 8-megapixel sensor.

The Nexus 5X and the Apple iPhone devices all come with a 5-megapixel front camera, with the 5X offering a 12.3-megapixel rear snapper like the Nexus 6P and the iPhone 6S and 6S Plus opting for a 12-megapixel shooter. Microsoft doesn't discuss the size of the pixels on its rear sensor, but both Apple and Google do, with Google's larger and therefore apparently better at absorbing more light for brighter images.

The Lumia devices sport a Natural flash, the iPhone devices a True Tone flash and the Nexus devices a dual flash. The iPhones also both come with a Retina flash for the front camera, which means your display will flash in order to provide more light in low light selfie scenarios.

As we mentioned, you'll find various features and functions on all six handsets. The Nexus handsets have IR laser assisted autofocus for example, while the Lumia devices have high resolution zoom. The iPhone 6S and the iPhone 6S Plus offer auto HDR and something called Live Photos, the latter of which automatically captures 1.5-seconds before and after the shot is taken for playback after.

The best plan here is to work out what features you want within your smartphone camera and then read the full reviews on how each of the devices perform in terms of camera. Nexus devices in the past haven't had the best camera reputation, while Lumia and iPhone both have good track records, but the new Nexus handsets could change this and vice versa for the Lumia devices. We were impressed with the iPhone 6S and iPhone 6S Plus and we will update this feature when we have reviewed the other handsets in full.

The Microsoft and Google devices are easier to compare in terms of hardware than Apple is as the former companies provide more specific information.

The Microsoft Lumia 950 and the Google Nexus 5X both opt for the Qualcomm Snapdragon 808 processor with Adreno 418 graphics. The Lumia 950 has 3GB of RAM compared to the Nexus 5X's 2GB however.

The Microsoft Lumia 950 XL and the Google Nexus 6P move to the newer Qualcomm Snapdragon 810 processors with Adreno 430 graphics and both sport 3GB of RAM so they should be similar in terms of hardware performance.

Apple's iPhone 6S and iPhone 6S Plus both feature the company's latest A9 processor and M9 motion coprocessor, the latter of which contributes to the iPhone's abilities to track your movement. It's difficult to tell how this compares to the Qualcomm chips, but once we have reviewed all devices in full, we will be sure to let you know if we experienced any issues with any of them. The iPhones were slick and smooth so no problems there.

In terms of storage, the only devices to offer microSD storage expansion are the Lumia handsets, both of which come in a 32GB internal memory option only. The iPhone 6S and iPhone 6S Plus come in 16GB, 64GB and 128GB options, while the Nexus 5X comes in 16GB and 32GB and the Nexus 6P in 32GB, 64GB and 128GB models.

Based on the available information, the Nexus 6P has the largest battery capacity at 3450mAh, while the Nexus 5X has the smallest at 2700mAh. That excludes the iPhones however as Apple only officially tells you how many hours you'll get out of the two devices and Google only tells you the capacities. Helpful right? Microsoft does give us both however.

The Lumia 950 comes with a 3000mAh battery that is said to offer 18 hours of 3G talk time and 12 hours standby, while the Lumia 950 XL's 3340mAh battery is said to deliver 19 hours talk time but still 12 days standby.

Apple says its iPhone 6S will offer 14 hours 3G talk time and 10 days standby, while the iPhone 6S Plus is said to provide 24 hours talk time and 16 days standby.

Here we arrive at the most interesting element of the comparison between these devices. The Microsoft Lumia 950 and Lumia 950 XL run on Windows 10, the Apple iPhone 6S and iPhone 6S Plus on iOS 9 and the Google Nexus 5X and Nexus 6P on Android 6.0 Marshmallow.

You have six devices, all of which run the latest respective software. They all have advantages and they all have features in their favour.

One of the highlights of the Windows 10 software is a seamless experience between your phone, PC, Xbox and tablet. You'll be able to connect the Lumia 950 and 950 XL to the Microsoft Display Dock that will then allow you to use your handset with an external monitor, keyboard and mouse for example.

The Office and Outlook apps will also scale up on the big-screen, providing a PC-like experience that is powered by your phone. There aren't many accessories that connect to Windows Phone however and the apps are more limited than Android or iOS platforms. That said, if you are a PC user, opting for the Lumia 950 or Lumia 950 XL will allow for a great experience across your devices.

When it comes to iOS, you have more options when it comes to apps and accessories than you do with Windows or Android, although the Android gap is closing. There is some integration with Apple computers with the Continuity feature but it's not quite as rich as the Windows option.

Apple's software has other things going for it though, especially in terms of ease of use. Its main advantage is that it has a very strong ecosystem whereby everyone develops for it, meaning compatibility with other apps or services is normally a certainty with iOS, whereas it might be in consideration or coming soon when it comes to Android or Windows.

Last but not least is Google's Android. This platform is the one for those who use Gmail or any of Google's other services because while it doesn't integrate with your computer, it delivers a great experience of Google's offerings in your hand and across the cloud.

It is also a fantastic platform when it comes to sharing and customisation, which are either harder or not possible on iOS or Windows Phone. In the case of Nexus, we are talking about raw Android and therefore you get the purest experience of the software, meaning all the latest features and functions. Marshmallow brings things like Now on Tap which is a clever recommendation service and Doze, which plans to save your battery.

The decision between these six devices will come down to various factors. How big a device do you want? How much are you willing to spend? What screen size do you want? Which software platform do you find the most appealing? Which design do you like the best?

Each of these devices is good in its own right. You could go for the one with the highest numbers on the spec sheet, which is probably the Lumia 950 XL or the Nexus 6P. Or you could go for the one that will suit you best based on what features it offers, which may be the iPhone, the smaller Nexus or the smaller Lumia.

There are pros and cons to each device and each software platform but that's why there are two flagship handsets on each platform to pick from. We will update this feature when we have reviewed the Nexus 5X, Nexus 6P and the Lumia 950 and Lumia 950 XL, but for now, read what we thought of the iPhone 6S and iPhone 6S Plus to see if either meets your requirements.